Restore unintentionally deleted Antora-related line.

Author: RaMisess

documentation/developer-guide/modules/tooling-guide/examples/GenerateJsonPayload.java

@@ -23,6 +23,7 @@
 import org.eclipse.esmf.metamodel.Aspect;
 import org.eclipse.esmf.metamodel.loader.AspectModelLoader;
 import org.junit.jupiter.api.Test;
+// end::imports[]
 
 public class GenerateJsonPayload extends AbstractGenerator {
    @Test